A lanthanide MOF-based gel material integrating sensing and capture, its preparation method and application

Abstract

This invention discloses a lanthanide MOF-based gel material integrating sensing and capture, its preparation method, and its application. The preparation method includes: Step 1, preparing Ln-MOF powder; Step 2, dispersing the Ln-MOF powder in water, adding gelatin, acrylamide, crosslinking agent N,N'-methylenebisacrylamide, and initiator persulfate, mixing evenly, and then carrying out a thermally initiated polymerization reaction, followed by cooling and molding to obtain a composite material in which Ln-MOF is dispersed in a gelatin-polyacrylamide dual-network hydrogel; Step 3, immersing the composite material obtained in Step 2 in an activated L-arginine solution to carry out an amidation reaction, allowing L-arginine to be grafted onto the hydrogel framework through amide bonds, thereby obtaining an L-arginine-functionalized dual-network hydrogel material. This invention effectively solves the problems of difficult powder recovery, poor water stability, insufficient adsorption sites, and weak adaptability to complex water bodies existing in the prior art.

Description

Technical Field

[0001] This invention relates to the field of uranium adsorption and sensing materials technology, specifically to a lanthanide MOF-based gel material integrating sensing and capture, its preparation method, and its application. Background Technology

[0002] Uranium, as a cornerstone raw material for nuclear power generation, plays a central role in driving the global energy transition. With the continued expansion of the uranium extraction industry, uranium is inevitably released into the environment, posing a significant threat to soil, surface water, and groundwater, with the risk of pollution increasing daily. U(VI) in particular exhibits high solubility and strong mobility in water, and its chemical toxicity can disrupt normal physiological metabolic processes. Therefore, efficient enrichment and detection of uranium in water bodies is a crucial measure for protecting human health, safeguarding environmental safety, and promoting sustainable development.

[0003] Lanthanide metal-organic frameworks (Ln-MOFs or Ln-MOFs) exhibit significant advantages in ion recognition and adsorption due to their unique optical properties and tunable structure. These materials combine the characteristic luminescence properties of lanthanides with the structural advantages of porous frameworks to form a unique bifunctional platform. They can generate characteristic peak emission under specific wavelength excitation, and due to the shielding effect of the ff transition of lanthanide ions, their luminescence signal exhibits outstanding anti-interference ability. Simultaneously, their high specific surface area and abundant active sites endow them with excellent ion adsorption performance. This synergistic mechanism of "luminescence response-pore confinement" makes Ln-MOFs an ideal candidate system for constructing bifunctional materials for sensing and adsorbing uranyl ions. After uranyl ions bind to Ln-MOF ligands, the "antenna effect" between lanthanide ions and ligands is suppressed, preventing the effective transfer of excited-state energy absorbed by the ligands to the lanthanide ions, leading to characteristic fluorescence quenching. The quantitative correlation between uranyl ion concentration and fluorescence intensity established based on this phenomenon provides a new method for uranium detection. However, as an integrated lanthanide MOF material for uranium sensing and capture, it faces the following challenges:

[0004] Question 1: Ln-MOFs face challenges in recycling and poor water stability when used in aquatic applications.

[0005] Ln-MOF materials are typically micron-sized powders, making them difficult to effectively recover from water using simple filtration methods. When treating large-scale industrial wastewater or natural water bodies, recovering dispersed Ln-MOF materials from large volumes of water is costly and inefficient, often resulting in material loss during the recovery process. Continuous recycling exacerbates material breakage, leading to a significant increase in solid-liquid separation costs. Furthermore, the fragility of Ln-MOFs in water is also a contributing factor to low detection sensitivity. When the material breaks down, its particle size becomes smaller and less uniform. On one hand, small-sized fragments are prone to agglomeration, resulting in poor dispersion of the material in water. This leads to uneven contact between uranyl ions and the material, with some materials failing to effectively interact with uranyl ions, thus affecting fluorescence signal generation. On the other hand, broken material scatters and absorbs light signals. In intact Ln-MOF materials, light signal generation and transmission are more ordered, resulting in higher fluorescence emission and collection efficiencies. When the material breaks, the scattering and absorption of light between the fragments increase, resulting in a weakening of the fluorescence signal intensity. This makes it difficult to accurately obtain the signal changes related to the uranyl ion concentration during detection, thus reducing the detection sensitivity.

[0006] Currently, the inventors have attempted to prepare Eu-MOF / polyacrylonitrile (PAN) composite fiber membranes using electrospinning technology. Specifically, they successfully prepared europium-doped metal-organic framework (Eu-MOFs or Eu-MOF) polyacrylonitrile (PAN) fiber membranes via electrospinning, followed by chitosan modification. The resulting membrane material (Eu-MOF / PAN-CS) exhibits excellent uranium adsorption capacity and high-sensitivity detection capability. In this system, PAN acts as a polymer scaffold, providing strong mechanical support for the composite material and effectively solving the inherent brittleness problem of pure MOFs. This composite structure significantly improves the stability of Eu-MOF in aqueous environments and enhances the material's reusability. This material provides an innovative solution for the precise capture and rapid monitoring of uranium in complex aquatic environments.

[0007] This strategy, with the support of the polymer matrix, also improves the recovery performance of MOF powder to some extent. However, electrospun fiber membranes have certain limitations in practical applications of Ln-MOFs loading and uranium sensing and capture: First, the fibers inside the membrane rely solely on physical entanglement to maintain the overall structure, lacking stable chemical cross-linking. During long-term use and multiple regeneration cycles, fiber breakage and loss of MOF active components are prone to occur, leading to a decline in material structural stability and reusability, making it difficult to meet the requirements of long-term continuous application. Second, during the post-grafting modification of the fiber membrane, the reaction reagents and conditions can easily disrupt the regular morphology of the fibers, causing fiber damage and pore size distortion, which in turn affects the dispersibility of MOF particles and the exposure of active sites. Third, the types and numbers of functional groups on the surface of the fiber membrane that can be used for uranyl ion coordination are relatively limited, resulting in a low adsorption capacity for uranyl ions, which restricts its application effect in actual water uranium treatment. To address the above-mentioned shortcomings of electrospun fiber membranes, this invention proposes using hydrogels as carriers for Ln-MOFs. The hydrogel possesses high mechanical strength, anti-swelling properties, and a three-dimensional porous structure. This structure not only provides a stable confined environment for Ln-MOFs, preventing their breakage and loss, but also enables uniform dispersion and firm anchoring of MOF particles through hydrogen bonds and interfacial forces within the pores.

[0008] Problem 2: The mechanical strength of the hydrogel is insufficient, making it difficult to achieve uniform dispersion and firm anchoring of MOF.

[0009] Single-network hydrogels exhibit low mechanical strength and poor resistance to swelling, making them prone to swelling deformation and structural softening in aqueous solutions, thus failing to provide stable support for Ln-MOFs. Furthermore, the simple physical mixing between the hydrogel and Ln-MOF results in weak interfacial bonding, making it difficult to achieve uniform dispersion of MOF particles. This leads to problems such as aggregation, sedimentation, and leakage, significantly reducing the utilization rate of active sites and resulting in insufficient structural stability, failing to meet the requirements for long-term stable practical applications.

[0010] Question 3: The dual-network gel loaded with Ln-MOFs exhibits poor uranium adsorption performance.

[0011] The dense structure of the gel easily forms a physical coating on Ln-MOF particles, burying some active sites and resulting in limited adsorption capacity and poor binding stability for uranyl ions. Simultaneously, the material lacks specific recognition sites, resulting in insufficient selective recognition of uranyl ions and low enrichment efficiency under low uranium concentration conditions, making it difficult to achieve efficient capture and deep removal of uranyl ions. Summary of the Invention

[0012] To address the problems existing in current technologies, this invention provides an integrated sensing-capture lanthanide MOF-based gel material, its preparation method, and its applications. The technical concept of this invention has the following characteristics:

[0013] To address problem 1, this invention employs a dual-network hydrogel in-situ encapsulation strategy. Eu-MOF is uniformly dispersed within a gelatin-polyacrylamide interpenetrating network. Through the physical encapsulation and cross-linking fixation of the polymer chains, the structural stability of Eu-MOF in water is significantly improved, preventing breakage, loss, and swelling collapse, thus achieving the goal of easy material recycling and reusability.

[0014] To address question 2, a high-strength interpenetrating double network structure is formed through the synergistic effect of physical cross-linking with gelatin and chemical cross-linking with polyacrylamide, significantly improving the mechanical strength, anti-swelling properties, and structural stability of the hydrogel. Simultaneously, by leveraging the spatial confinement effect, hydrogen bonding, and interfacial forces of the three-dimensional network, uniform dispersion and firm anchoring of Eu-MOF crystals within the hydrogel channels are achieved, effectively preventing MOF particle aggregation, sedimentation, and leakage, ensuring full exposure of active sites, and enhancing structural stability and lifespan.

[0015] To address problem 3, this invention grafts L-arginine. The carboxyl groups in the dual-network hydrogel react with the amino groups of L-arginine to form amide bonds, providing more effective binding sites for the adsorption of uranyl ions, thereby significantly improving the material's adsorption performance for uranium. Furthermore, the in-situ grafting of L-arginine onto the dual-network hydrogel framework simultaneously introduces multiple types of highly efficient coordination active sites, including amino, carboxyl, and guanidine groups. These sites, together with the Eu-MOF's own ligand sites, form a multi-functional synergistic coordination effect, greatly enhancing the chelation ability and binding strength for uranyl ions, significantly improving adsorption capacity and specific recognition selectivity, and achieving highly efficient capture of uranyl ions.

[0016] Based on the above-described inventive concept, in a first aspect, the present invention provides a method for preparing an integrated sensing-capture lanthanide MOF-based gel material, comprising the following steps:

[0017] Step 1: Prepare lanthanide metal-organic framework (Ln-MOF) powder;

[0018] Step 2: Disperse the Ln-MOF powder obtained in Step 1 in water, add gelatin, acrylamide, crosslinking agent N,N'-methylenebisacrylamide and initiator persulfate, mix evenly, carry out thermally initiated polymerization reaction, and then cool down to form a composite material in which Ln-MOF is dispersed in gelatin-polyacrylamide double network hydrogel.

[0019] Step 3: Activate L-arginine with an activator, immerse the composite material obtained in Step 2 in the activated L-arginine solution, and carry out an amidation reaction to graft L-arginine onto the hydrogel framework through amide bonds, thereby obtaining an L-arginine-functionalized dual-network hydrogel material.

[0020] Further, in step one, the Ln-MOF is Eu-MOF, and its preparation process includes: mixing europium source and organic ligand H3TATAB in a mixed solvent of N,N-dimethylformamide and water, and hydrothermally reacting at 80-120°C for 48-96 hours.

[0021] Furthermore, the europium source is one or more of europium nitrate, europium chloride, and europium sulfate.

[0022] Furthermore, in step two, the amount of Ln-MOF powder added is 0.1-0.6 grams per 17 ml of water; the conditions for the thermally initiated polymerization reaction are: temperature 50-70℃, time 1-5 hours.

[0023] Furthermore, in step three, the amount of L-arginine used is 0.6968-2.0904 g per 100 mL of solution; the conditions for the amidation reaction are: temperature 20-30℃, time 12-24 hours.

[0024] Furthermore, in step three, the persulfate is one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0025] Furthermore, in step three, the activator includes N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

[0026] Furthermore, the preparation method includes the following steps:

[0027] Step 1, Preparation of Eu-MOF powder: Eu(NO3)3·6H2O is dissolved in DMF solution, and H3TATAB (i.e., 2,4,6-tris[(p-carboxyphenyl)amino]-1,3,5-triazine) is dissolved in H2O. The mixture of the two solutions is stirred in a beaker, ultrasonically mixed, and then transferred to a hydrothermal reactor. It is heated at 80℃-120℃ for 48-96h. After the reaction system is naturally cooled to 25℃, the initial product is collected by centrifugation, filtered to obtain small rod-shaped crystals suitable for X-ray data acquisition, and then washed several times with DMF, H2O and methanol, air-dried, and dried in a vacuum oven.

[0028] Step 2, Preparation of Ln-MOF / Gelatin-PAM DN: The synthesized Eu-MOF powder was uniformly dispersed in deionized water under ultrasonic treatment. Then, gelatin, acrylamide and N,N'-methylenebisacrylamide were added at 45°C. After the gelatin was completely dissolved, potassium persulfate was added to dissolve it completely. The entire system was reacted at 60°C for 1-5 hours. After the reaction was completed, the solution was transferred to a mold and kept in an ice-water bath at 4°C for at least 0.5 hours to obtain the double-network hydrogel Ln-MOF / Gelatin-PAM DN.

[0029] Step 3, Preparation of Arg@Ln-MOF / Gelatin-PAM DN: N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were dissolved sequentially in deionized water and stirred thoroughly until completely dissolved. L-arginine was then added and stirring continued until homogeneous and transparent to form an activated solution. The prepared Ln-MOF / Gelatin-PAM DN dual-network hydrogel was completely immersed in the above activated solution and reacted at a constant temperature of 20-30 ℃ for 12-24 h. After the reaction was completed, the hydrogel was removed and washed repeatedly with deionized water several times to remove unreacted residual reagents, thus obtaining the L-arginine-functionalized dual-network hydrogel material Arg@Ln-MOF / Gelatin-PAM DN.

[0030] In a second aspect, the present invention provides a lanthanide MOF-based gel material for sensing and capturing integrated materials prepared according to the preparation method described above.

[0031] In a third aspect, the present invention provides the application of a lanthanide MOF-based gel material for sensing and capturing integrated lanthanide MOF prepared according to the preparation method described above in the adsorption and / or detection of uranyl ions in water.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. This invention achieves controllable crystallization growth of metal-organic framework materials, using a hydrothermal method to prepare Eu-MOF powder, which exhibits typical red light emission characteristics under ultraviolet light excitation, displaying a characteristic emission peak of 615 nm at an excitation wavelength of 340 nm. Addressing the inherent fragility and insufficient structural stability of Eu-MOF materials in water, this invention uniformly embeds Eu-MOF within a gelatin / polyacrylamide dual-network hydrogel framework. This method preserves the Eu-MOF crystal structure and characteristic red fluorescence properties while fundamentally solving the problems of easy breakage, easy loss, difficulty in recycling, and poor stability of Ln-MOF powder in water. The interpenetrating dual-network structure provides flexible support for Eu-MOF, significantly improving the material's structural stability and mechanical strength in aqueous solutions, avoiding fluorescence scattering and decreased detection sensitivity due to material breakage, effectively improving its fragility, and enabling convenient recycling and reuse of the gel material.

[0034] 2. This invention utilizes a high-strength dual network formed by gelatin and polyacrylamide to significantly improve the mechanical properties, anti-swelling properties, and structural stability of the hydrogel. Simultaneously, it achieves uniform dispersion and firm anchoring of Eu-MOF within the three-dimensional channels, preventing aggregation, sedimentation, and leakage, and ensuring full exposure of active sites. Furthermore, by grafting L-arginine, multiple coordination sites, including amino, carboxyl, and guanidine groups, are simultaneously introduced into the hydrogel framework. These sites form synergistic coordination with the Eu-MOF's own coordination sites, greatly enhancing the chelation ability and adsorption affinity for uranyl ions, significantly improving adsorption capacity and adsorption rate, and exhibiting excellent uranium capture performance under optimal pH 6 conditions.

[0035] 3. This invention constructs a fluorescence signal response model for the Arg@Ln-MOF / Gelatin-PAM DN composite material, deeply exploring its intrinsic correlation with changes in uranyl ion concentration, and successfully establishes a quantitative detection method for uranium ions based on fluorescence intensity changes. The fluorescence intensity of Arg@Ln-MOF / Gelatin-PAM DN exhibits a regular quenching phenomenon with increasing uranyl ion concentration, the core mechanism of which stems from the energy transfer blocking effect caused by coordination competition. When UO22+ ions are present in the system, the empty 5f orbital of the uranyl ion exhibits strong electron acceptance ability, preferentially coordinating with the carboxylic acid oxygen and pyridine nitrogen containing lone pairs of electrons in the ligand molecule to form stable coordination bonds. This coordination behavior leads to a redistribution of the electron cloud density of the ligand, significantly increasing its lowest unoccupied molecular orbital (LUMO) energy level, breaking the original ligand-Eu bond. 3+ The energy level matching relationship between ions leads to the interruption of energy transfer pathways, preventing the light energy absorbed by the ligand from being effectively transferred to Eu. 3+The ions are dissipated in a non-radiative manner, ultimately resulting in a significant decrease in the material's fluorescence intensity. A quantitative model of the relationship between fluorescence intensity and uranium ion concentration was established by nonlinearly fitting fluorescence data under different concentrations of uranium ions. The detection limit for uranium ions in this material reaches 1.86 ppb (3σ criterion), with a linear correlation coefficient R0. 2 =0.99. Batch adsorption experiments showed that, under the optimal adsorption condition of pH 6.0, the Arg@Ln-MOF / Gelatin-PAM DN bifunctional hydrogel prepared in this invention achieved an adsorption capacity of 230.9 mg / g for uranyl ions. This adsorption performance is significantly better than that of MOF-supported electrospun fiber membranes, which have a uranium adsorption capacity of only 201.88 mg / g under the same optimal pH=6.0 condition. This fully demonstrates that the Arg@Ln-MOF / Gelatin-PAM DN bifunctional hydrogel prepared in this invention has a more prominent advantage in the efficient capture of uranyl ions, effectively solving the inherent defect of low adsorption capacity of electrospun fiber membranes.

[0036] In summary, the lanthanide MOF-based dual-network hydrogel material with integrated sensing and capture obtained by this invention effectively solves the problems of difficult powder recovery, poor water stability, insufficient adsorption sites, and weak adaptability to complex water bodies in existing technologies. The prepared Arg@Ln-MOF / Gelatin-PAM DN composite hydrogel has excellent uranium adsorption performance, fluorescence sensing performance, and cycling stability, and has broad application prospects in nuclear wastewater treatment, seawater uranium extraction, and radioactive pollution control. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the preparation process of the present invention;

[0038] Figure 2 This is the Fourier transform infrared spectrum of the Arg@Ln-MOF / Gelatin-PAM DN used in this invention.

[0039] Figure 3 This is a scanning electron microscope image of Arg@Ln-MOF / Gelatin-PAM DN in this invention.

[0040] Figure 4 Experimental graphs showing the uranium adsorption capacity of Ln-MOF / Gelatin-PAM DN and Arg@Ln-MOF / Gelatin-PAM DN as uranium adsorbents under different pH conditions.

[0041] Figure 5The fluorescence intensity is the result of Arg@Ln-MOF / Gelatin-PAM DN adsorbing different concentrations of uranyl ions in this invention. Detailed Implementation

[0042] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment describes a method for preparing a lanthanide MOF-based gel material that integrates sensing and capture, comprising the following steps:

[0045] Step 1: Preparation of Eu-MOF powder: Eu(NO3)3·6H2O (0.4 mmol, 0.1784 g) was dissolved in 12 mL of DMF solution, and H3TATAB (0.2 mmol, 0.1000 g) was dissolved in 8 mL of H2O. The mixture of the two solutions was stirred in a beaker for 10 min, ultrasonically mixed, and then transferred to a 50 mL hydrothermal reactor. The mixture was heated at 100 °C for 72 h. After the reaction system was naturally cooled to 25 °C, the initial product was collected by centrifugation (8000 rpm, 10 min). Small rod-shaped crystals suitable for X-ray data acquisition were obtained by filtration, then washed several times with DMF, H2O, and methanol, air-dried, and dried in a vacuum oven at 70 °C for 24 h.

[0046] Step 2: Preparation of Ln-MOF / Gelatin-PAM DN: 0.1 g of synthesized Eu-MOF was uniformly dispersed in 17 mL of deionized water under ultrasonic treatment and sonicated for 1 hour. Then, 0.67 g of gelatin, 2.857 g of acrylamide (AM), and 0.02178 g of N,N'-methylenebisacrylamide (MBA) were added at 45°C. After the gelatin was completely dissolved, 0.03015 g of potassium persulfate (KPS) was added to completely dissolve the gelatin. The entire system was reacted at 60°C for 1 hour. After the reaction was complete, the solution was transferred to a mold and kept in an ice-water bath at 4°C for 0.5 hours to obtain the double-network hydrogel Ln-MOF / Gelatin-PAM DN.

[0047] Step 3: Preparation of Arg@Ln-MOF / Gelatin-PAM DN: N-hydroxysuccinimide (0.14375 g) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (0.9685 g) were dissolved sequentially in 100 mL of deionized water. After thorough stirring until completely dissolved, L-arginine (0.6968 g) was added and stirring continued until homogeneous and transparent. The prepared Ln-MOF / Gelatin-PAM DN dual-network hydrogel was completely immersed in the above activation solution and reacted at 25 ℃ for 18 h. After the reaction, the hydrogel was removed and washed repeatedly with deionized water several times to remove unreacted residual reagents, thus obtaining the L-arginine-functionalized dual-network hydrogel material Arg@Ln-MOF / Gelatin-PAM DN.

[0048] See Figures 1-4 As shown, Figure 1 A schematic diagram of the preparation process of Arg@Ln-MOF / Gelatin-PAM DN in this embodiment is shown.

[0049] Figure 2 The Fourier transform infrared spectrum of Arg@Ln-MOF / Gelatin-PAM DN is shown.

[0050] Figure 3 The image shown is a scanning electron microscope image of Arg@Ln-MOF / Gelatin-PAM DN. Figure 2 Fourier transform infrared spectrum and Figure 3 Scanning electron microscopy images confirmed the successful preparation of the L-arginine-functionalized dual-network hydrogel material Arg@Ln-MOF / Gelatin-PAM DN.

[0051] Figure 4 This is an experimental graph showing the uranium adsorption capacity of Ln-MOF / Gelatin-PAM DN and Arg@Ln-MOF / Gelatin-PAM DN as uranium adsorbents under different pH conditions.

[0052] from Figure 4 It can be seen that the uranium adsorption capacity of Arg@Ln-MOF / Gelatin-PAM DN is greater than that of Ln-MOF / Gelatin-PAM DN at pH = 3-9, and this difference in uranium adsorption capacity becomes the greatest at pH = 6.0.

[0053] Figure 5The fluorescence intensity of Arg@Ln-MOF / Gelatin-PAM DN after adsorption of different concentrations of uranyl ions is shown. Within the uranyl ion concentration range of 0–19 mg / L, the fluorescence decay of Arg@Ln-MOF / Gelatin-PAM DN exhibits a linear relationship with concentration, with a fitting correlation coefficient reaching R0. 2 =0.99.

[0054] Example 2

[0055] The preparation method in this embodiment is basically the same as that in Example 1, except that the hydrothermal reaction temperature in step one is 120°C.

[0056] In this embodiment, the increase in hydrothermal temperature promotes better lattice arrangement, making the crystal more complete.

[0057] Example 3

[0058] The preparation method described in this embodiment is basically the same as that in Example 2, except that the amount of Eu-MOF added in step two is 0.4g.

[0059] In this embodiment, the fluorescence performance of the material is significantly improved with the increase of Eu-MOF content. Further increasing the Eu-MOF content beyond 0.6 g leads to uneven dispersion of the Eu-MOF in the hydrogel, resulting in sedimentation.

[0060] Example 4

[0061] The preparation method described in this embodiment is basically the same as that in Example 3, except that in step two, the entire system reacts at 60°C for 3 hours.

[0062] In this embodiment, the aforementioned precursor solution was subjected to thermally initiated polymerization at 60 °C. The polymerization time significantly affects the gel formation state, generally ranging from 1 to 5 hours. Too short a reaction time leads to incomplete polymerization and insufficient gel strength. Too long a reaction time causes excessive cross-linking of the system, premature gel solidification, which is detrimental to structural uniformity and the formation of the dual-network structure. To ensure sufficient formation of the dual-network structure without over-solidification, the optimal polymerization reaction time was determined to be 3 hours.

[0063] Example 5

[0064] The preparation method in this embodiment is basically the same as that in Example 4, except that 1.3936 g of L-arginine is added in step three.

[0065] Example 6

[0066] The preparation method in this embodiment is basically the same as that in Example 4, except that in step three, 2.0904 g of L-arginine is added.

[0067] The typical addition amount of L-arginine is 0.6968-2.0904 g. Insufficient L-arginine results in a limited number of active coordination sites (amino, carboxyl, guanidine, etc.) that can be grafted onto the hydrogel surface, leading to low adsorption capacity and minimal selectivity improvement. Excessive L-arginine, on the other hand, causes physical accumulation and aggregation of arginine molecules on the hydrogel surface and within the pores, blocking the three-dimensional pore structure and reducing the specific surface area. Furthermore, excessive arginine can shield the fluorescent sites of Eu-MOF, resulting in weakened fluorescence signals and decreased detection sensitivity.

[0068] Example 7

[0069] The preparation method described in this embodiment is basically the same as that in Example 5, except that the reaction temperature in step three is 30 °C.

[0070] The reaction in step three is generally carried out at a constant temperature of 20-30 °C for 12-24 h. Appropriately increasing the reaction temperature can accelerate the amidation reaction rate between L-arginine and Ln-MOF / Gelatin-PAM DN.

[0071] Example 8

[0072] The preparation method described in this embodiment is basically the same as that in Example 7. The difference is that in step three, the prepared Ln-MOF / Gelatin-PAM DN double network hydrogel is immersed in the solution and reacted at a constant temperature of 30 °C for 24 h.

[0073] In this embodiment, it is ensured that L-arginine reacts fully with Ln-MOF / Gelatin-PAM DN to form a stable amide bond.

[0074] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a lanthanide MOF-based gel material integrating sensing and capture, characterized in that, Includes the following steps: Step 1: Prepare lanthanide metal-organic framework (Ln-MOF) powder, wherein the Ln-MOF is Eu-MOF; Step 2: Disperse the Ln-MOF powder obtained in Step 1 in water, add gelatin, acrylamide, crosslinking agent N,N'-methylenebisacrylamide and initiator persulfate, mix evenly, carry out thermally initiated polymerization reaction, and then cool down to form a composite material in which Ln-MOF is dispersed in gelatin-polyacrylamide double network hydrogel. Step 3: Activate L-arginine with an activator, immerse the composite material obtained in Step 2 in the activated L-arginine solution, and carry out an amidation reaction to graft L-arginine onto the hydrogel framework through amide bonds, thereby obtaining an L-arginine-functionalized dual-network hydrogel material.

2. The preparation method according to claim 1, characterized in that, In step one, the preparation process of the Eu-MOF includes: mixing europium source and organic ligand H3TATAB in a mixed solvent of N,N-dimethylformamide and water, and hydrothermally reacting at 80-120°C for 48-96 hours.

3. The preparation method according to claim 2, characterized in that, The europium source is one or more of europium nitrate, europium chloride, and europium sulfate.

4. The preparation method according to claim 1, characterized in that, In step two, the amount of Ln-MOF powder added is 0.1-0.6 g per 17 ml of water; the conditions for the thermally initiated polymerization reaction are: temperature 50-70℃, time 1-5 hours.

5. The preparation method according to claim 1, characterized in that, In step three, the amount of L-arginine used is 0.6968-2.0904 g per 100 mL of solution; the conditions for the amidation reaction are: temperature 20-30℃, time 12-24 hours.

6. The preparation method according to claim 1, characterized in that, In step three, the persulfate is one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

7. The preparation method according to claim 1, characterized in that, In step three, the activator includes N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

8. The preparation method according to claim 1, characterized in that, Includes the following steps: Step 1, Preparation of Eu-MOF powder: Eu(NO3)3·6H2O is dissolved in DMF solution, and H3TATAB is dissolved in H2O. The mixture of the two solutions is stirred in a beaker, ultrasonically mixed, and then transferred to a hydrothermal reactor. It is heated at 80℃-120℃ for 48-96h. After the reaction system is naturally cooled to 25℃, the initial product is collected by centrifugation, filtered to obtain small rod-shaped crystals suitable for X-ray data acquisition, and then washed several times with DMF, H2O and methanol, air-dried, and dried in a vacuum oven. Step 2, Preparation of Ln-MOF / Gelatin-PAM DN: The synthesized Eu-MOF powder was uniformly dispersed in deionized water under ultrasonic treatment. Then, gelatin, acrylamide and N,N'-methylenebisacrylamide were added at 45°C. After the gelatin was completely dissolved, potassium persulfate was added to dissolve it completely. The entire system was reacted at 60°C for 1-5 hours. After the reaction was completed, the solution was transferred to a mold and kept in an ice-water bath at 4°C for at least 0.5 hours to obtain the double-network hydrogel Ln-MOF / Gelatin-PAM DN. Step 3, Preparation of Arg@Ln-MOF / Gelatin-PAM DN: N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were dissolved sequentially in deionized water and stirred thoroughly until completely dissolved. L-arginine was then added and stirring continued until homogeneous and transparent to form an activated solution. The prepared Ln-MOF / Gelatin-PAM DN dual-network hydrogel was completely immersed in the above activated solution and reacted at a constant temperature of 20-30 ℃ for 12-24 h. After the reaction was completed, the hydrogel was removed and washed repeatedly with deionized water several times to remove unreacted residual reagents, thus obtaining the L-arginine-functionalized dual-network hydrogel material Arg@Ln-MOF / Gelatin-PAM DN.

9. A lanthanide MOF-based gel material for sensing and capturing integrated materials, prepared according to any one of claims 1-7.

10. The application of the integrated lanthanide MOF-based gel material for sensing and capturing prepared according to any one of claims 1-7 in the adsorption and / or detection of uranyl ions in water.

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